We show results for the ${\rm Y}$ spectrum calculated in lattice QCD including for the first time vacuum polarization effects for light $u$ and $d$ quarks as well as $s$ quarks. We use gluon field configurations generated by the MILC collaboration. The calculations compare the results for a variety of $u$ and $d$ quark masses, as well as making a comparison to quenched results (in which quark vacuum polarization is ignored) and results with only $u$ and $d$ quarks. The $b$ quarks in the ${\rm Y}$ are treated in lattice Nonrelativistic QCD through NLO in an expansion in the velocity of the $b$ quark. We concentrate on accurate results for orbital and radial splittings where we see clear agreement with experiment once $u$, $d$ and $s$ quark vacuum polarization effects are included. This now allows a consistent determination of the parameters of QCD. We demonstrate this consistency through the agreement of the ${\rm Y}$ and $B$ spectrum using the same lattice bare $b$ quark mass. A one-loop matching to continuum QCD gives a value for the $b$ quark mass in full lattice QCD for the first time. We obtain $m_b^{\overline{\mathrm{MS}}}(m_b^{\overline{\mathrm{MS}}})=4.4(3)\mathrm{GeV}$. We are able to give physical results for the heavy quark potential parameters, $r_0=0.469(7)\mathrm{fm}$ and $r_1=0.321(5)\mathrm{fm}$. Results for the fine structure in the spectrum and the ${\rm Y}$ leptonic width are also presented. We predict the ${\rm Y}-{\eta }_b$ splitting to be 61(14) MeV, the ${{\rm Y}}^{\prime }-{\eta }_b^{\prime }$ splitting as 30(19) MeV and the splitting between the $h_b$ and the spin-average of the ${\chi }_b$ states to be less than 6 MeV. Improvements to these calculations that will be made in the near future are discussed.

A self-consistent large $N_c$ approach is developed for the collective quantization of $SU(3)$ flavor hedgehog solitons, such as the Skyrmion. The key to this analysis is the determination of all of the zero-modes associated with small fluctuations around the hedgehog. These are used in the conventional way to construct collective coordinates. This approach differs from previous work in that it does not implicitly assume that each static zero-mode is associated with a dynamical zero-mode. It is demonstrated explicitly in the context of the Skyrmion that there are fewer dynamical zero-modes than static ones due to the Witten-Wess-Zumino term in the action. Group-theoretic methods are employed to identify the physical states resulting from canonical quantization of the collectively rotating soliton. The collective states fall into representations of $SU(3)$ flavor labeled by $(p,q)$ and are given by $(2J,\frac{Nc}{2}-J)$ where $J=\frac{1}{2},\frac{3}{2},\cdots$ is the spin of the collective state. States with strangeness $S>0$ do not arise as collective states from this procedure; thus the ${\theta }^{+}$ (pentaquark) resonance does not arise as a collective excitation in models of this type.

We reexmine some proposals of black hole entropy in loop quantum gravity (LQG) and consider a new possible choice of the Immirzi parameter which has not been pointed out so far. We also discuss the fact that a new idea is inevitable if we regard the relation between the area spectrum in LQG and the relation between the area spectrum in the quasinormal mode analysis seriously.

This paper is devoted to the study of the dynamics of a non-BPS $\mathrm{D}p$-brane at the tachyon vacuum that moves in the curved background.

We study the cosmological evolution of the volume moduli in a class of recently proposed inflationary universe models of Kachru et al. arising out of Type IIB string theory, where a number of the moduli fields have been stabilized through flux compactifications. Developing an approach introduced by some of us earlier, we show, in agreement with Brustein et al., how the presence of extra sources of matter act so as to provide additional friction, slowing the modulus field as it evolves down its potential, thereby vastly increasing the region of parameter space which leads to the eventual stabilization of these fields. Extending the case to include both the real and imaginary parts of the volume modulus, we show how the parameter space of initial conditions is modified and comment on the impact for these inflationary models arising out of flux type compactifications.

Rozowsky, Volkas and Wali [J. Rozowsky, R. Volkas, and K. Wali, Phys. Lett. B 580, 249 (2004).] recently found interesting numerical solutions to the field equations for a gauged $U(1)\otimes U(1)$ scalar field model. Their solutions describe a reflection-symmetric domain wall with scalar fields and coupled gauge configurations that interpolate between constant magnetic fields on one side of the wall and exponentially decaying ones on the other side. This corresponds physically to an infinite sheet of supercurrent confined to the domain wall with a linearly rising gauge potential on one side and Meissner suppression on the other. While it was shown that these static solutions satisfied the field equations, their stability was left unresolved. In this paper, we analyze the normal modes of perturbations of the static solutions to demonstrate their perturbative stability.

We reconstruct the shape of the primordial power spectrum (PPS) using a smoothing spline. Our adapted smoothing spline technique provides a complementary method to existing efforts to search for smooth features in the PPS, such as a running spectral index. With this technique we find no significant indication with Wilkinson Microwave Anisotropy Probe first-year data that the PPS deviates from a Harrison-Zeldovich spectrum and no evidence for loss of power on large scales. We also examine the effect on the cosmological parameters of the additional PPS freedom. Smooth variations in the PPS are not significantly degenerate with other cosmological parameters, but the spline reconstruction greatly increases the errors on the optical depth and baryon fraction.

We present an analysis of the constraining power of future measurements of the integrated Sachs-Wolfe (ISW) effect on models of the equation of state of dark energy as a function of redshift, $w(z)$. To achieve this, we employ a new parametrization of $w$, which utilizes the mean value of $w(z)$ ($⟨w⟩$) as an explicit parameter. This helps to separate the information contained in the estimation of the distance to the last scattering surface (from the cosmic microwave background (CMB)) from the information contained in the ISW effect. We then use Fisher analysis to forecast the expected uncertainties in the measured parameters from future ISW observations for two models of dark energy with very different time evolution properties. For example, we demonstrate that the cross correlation of Planck CMB data and large synoptic survey telescope (LSST) galaxy catalogs will provide competitive constraints on $w(z)$, compared to a supernovae acceleration probe (SNAP)-like supernovae (SNe) project, for models of dark energy with a rapidly changing equation of state (e.g. Kink models). Our work confirms that, while SNe measurements are more suitable for constraining variations in $w(z)$ at low redshift, the ISW effect can provide important independent constraints on $w(z)$ at high $z$.

Flat Friedmann-Robertson-Walker (FRW) perfect fluid cosmologies can be reproduced as particular solutions of suitable field-theoretical models. Here we investigate the stability of perfect fluid model trajectories with respect to sets of trajectories of the corresponding field models having generic initial conditions. It is shown that the trajectories of barotropic perfect fluid models and those of the Chaplygin gas model are stable. The total probability to reach the Chaplygin gas regime early enough to achieve a matter dominated stage having a realistic duration is calculated for a scalar field model assuming a natural measure in the space of initial conditions taken near a cosmological singularity. An example is presented of a two-fluid cosmological model where the stability is partially absent.

We study the prospects for detecting gamma rays from dark matter (DM) annihilations in enhancements of the DM density (mini-spikes) around intermediate-mass black holes (IMBH) with masses in the range ${10}^2\lesssim M/{\mathrm{M}}_{\odot }\lesssim {10}^6$. Focusing on two different IMBH formation scenarios, we show that, for typical values of mass and cross section of common DM candidates, mini-spikes, produced by the adiabatic growth of DM around pregalactic IMBHs, would be bright sources of gamma rays, which could be easily detected with large field-of-view gamma-ray experiments such as GLAST, and further studied with smaller field-of-view, larger-area experiments like Air Cherenkov Telescopes CANGAROO, HESS, MAGIC, and VERITAS. The detection of many gamma-ray sources not associated with a luminous component of the Local Group, and with identical cutoffs in their energy spectra at the mass of the DM particle, would provide a potential smoking-gun signature of DM annihilations and shed new light on the nature of intermediate and supermassive black holes.

We extend the WKB method for the computation of cosmological perturbations during inflation beyond leading order and provide the power spectra of scalar and tensor perturbations to second order in the slow-roll parameters. Our method does not require that the slow-roll parameters be constant. Although leading and next-to-leading results in the slow-roll parameters depend on the approximation technique used in the computation, we find that the inflationary theoretical predictions obtained may reach the accuracy required by planned observations. In two technical appendixes, we compare our technique and results with previous findings.

The detection of gravitational waves is a very active research field at the moment. In Brazil the gravitational wave detector is called Mario SCHENBERG. Because of its high sensitivity it is necessary to model mathematically all known noise sources so that digital filters can be developed that maximize the signal-to-noise ratio. One of the noise sources that must be considered are the disturbances caused by electromagnetic pulses due to lightnings close to the experiment. Such disturbances may influence the vibrations of the antenna’s normal modes and mask possible gravitational wave signals. In this work we model the interaction between lightnings and SCHENBERG antenna and calculate the intensity of the noise due to a close lightning stroke in the detected signal. We find that the noise generated does not disturb the experiment significantly.

We present a method of searching for, and parametrizing, signals from known radio pulsars in data from interferometric gravitational wave detectors. This method has been applied to data from the LIGO and GEO 600 detectors to set upper limits on the gravitational wave emission from several radio pulsars. Here we discuss the nature of the signal and the performance of the technique on simulated data. We show how to perform a coherent multiple detector analysis and give some insight into the covariance between the signal parameters.

In this note we examine the constraints imposed by muon anomalous magnetic moment ($(g-2{)}_{\mu }$) and ${\mu }^{-}\to e^{+}{e}^{-}{e}^{-}$ on lepton number violating (LNV) couplings of the triplet Higgs in Little Higgs (LH) model.

As a first step in the aim of arriving at a differential description of neutral Higgs boson decays into heavy quarks, $h\to Q\overline{Q}X$, to second order in the QCD coupling ${\alpha }_S$, we have computed the $hQ\overline{Q}$ amplitude at the two-loop level in QCD for a general neutral Higgs boson which has both scalar and pseudoscalar couplings to quarks. This amplitude is given in terms of a scalar and a pseudoscalar vertex form factor, for which we present closed analytic expressions in terms of one-dimensional harmonic polylogarithms of maximum weight 4. The results hold for arbitrary four-momentum squared, $q^2$, of the Higgs boson and of the heavy-quark mass, $m$. Moreover, we derive the approximate expressions of these form factors near threshold and in the asymptotic regime $m^2/q^2\ll 1$.

A new SO(10) unified model is proposed based on a one-step breaking of SO(10) to the standard model gauge group $\mathrm{SU}(3{)}_C\times \mathrm{SU}(2{)}_L\times \mathrm{U}(1{)}_Y$ using a single 144 of Higgs. The symmetry breaking occurs when the SU(5) 24-plet component of 144 develops a vacuum expectation value. Further, it is possible to obtain from the same 144 a light Higgs doublet necessary for electroweak symmetry breaking using recent ideas of string vacua landscapes and fine-tuning. Thus the breaking of SO(10) down to $\mathrm{SU}(3{)}_C\times \mathrm{U}(1{)}_{em}$ can be accomplished with a single Higgs. We analyze this symmetry breaking pattern in the nonsupersymmetric as well as in the supersymmetric SO(10) model. In this scenario masses of the quarks and leptons arise via quartic couplings. We show that the resulting mass pattern is consistent with experimental data, including neutrino oscillations. The model represents an alternative to the currently popular grand unified scenarios.

The design and implementation of large sets of spatially extended, gauge-invariant operators for use in determining the spectrum of baryons in lattice QCD computations are described. Group-theoretical projections onto the irreducible representations of the symmetry group of a cubic spatial lattice are used in all isospin channels. The operators are constructed to maximize overlaps with the low-lying states of interest, while minimizing the number of sources needed in computing the required quark propagators. Issues related to the identification of the spin quantum numbers of the states in the continuum limit are addressed.

We elaborate on a recently proposed extension of the Gerasimov-Drell-Hearn (GDH) sum rule which is achieved by taking derivatives with respect to the anomalous magnetic moment. The new sum rule features a linear relation between the anomalous magnetic moment and the dispersion integral over a cross section quantity. We find some analogy of the linearized form of the GDH sum rule with the “sideways dispersion relations.” As an example, we apply the linear sum rule to reproduce the famous Schwinger’s correction to the magnetic moment in QED from a tree-level cross section calculation and outline the procedure for computing the two-loop correction from a one-loop cross section calculation. The polarizabilities of the electron in QED are considered as well by using the other forward-Compton-scattering sum rules. We also employ the sum rules to study the magnetic moment and polarizabilities of the nucleon in a relativistic chiral effective field theory (EFT) framework. In particular we investigate the chiral extrapolation of these quantities.

We study quantitatively angular correlations in the two-particle spectrum produced by an energetic probe scattering off a dense hadronic target with sizable saturation momentum. To this end, two-parton inclusive cross sections for arbitrary projectiles with small color charge density are derived in the eikonal formalism. Our results are the following: For large momenta of the observed particles, the perturbative limit with characteristic back-to-back correlation is recovered. As the trigger momenta get closer to the saturation scale $Q_s$, the angular distribution broadens. When the momenta are significantly smaller than $Q_s$, the azimuthal distribution is broad but still peaked back-to-back. However, in a narrow momentum range $(0.5÷1.5)Q_s$, we observe that the azimuthal correlation splits into a double peak with maxima displaced away from $180°$. We argue that it is the soft multiple scattering physics that is responsible for the appearance of this shift in the angle of maximal correlation. We also point out that when the physical size of the projectile is particularly small, the double peak structure persists in a significantly wider range of final state momenta.